By way of introduction, it is known that the parts obtained from stacks of composite material (composites), such as for example those formed by sheets of resin preimpregnated carbon fibers or glass fibers (prepregs), are widely used in the industry, for example as components in the aeronautical industry such as stringers, stiffeners and structural reinforcements. These components are distinguished by their low weight and great mechanical strength (specific strength).
One of the technologies existing for forming stacks of composite material continuously is based on a roller and mandrel (roll-forming) system originally conceived for manufacturing metal sections. The metal rollers press the composite material against the surface of the mandrel compacting the composite material and giving it the shape of the mandrel. The obtained part is subsequently cured.
U.S. Pat. No. 7,249,943 describes an apparatus for forming stiffeners and other composite reinforcing elements, comprising a base the upper part of which has a longitudinal mandrel with the shape to be given to the sheet arranged thereon, as well as one or several rollers assembled in one or several supports, such that the rollers roll over the composite material pressing it against the mandrel for forming it and obtaining the composite part with the desired geometry and ready to be cured. The running surface of the rollers has a configuration complementary to the cross-section of the mandrel. Although this apparatus allows manufacturing straight structural sections with changes in thickness and curved, it is not capable of manufacturing more complex geometries, such as for example geometries with changes in plane to overcome obstacles (joggles), twisted geometries, etc.
Furthermore, even for obtaining simple geometric shapes such as omega-shaped components for example, it is necessary to have several rollers, all of which have their respective pressure adjustment systems, which complicates and makes the structure of such systems more expensive and jeopardizes the quality of the part obtained due to the occurrence of creases when the rollers act on the composite material.
Additionally, when working with solid rollers for more or less rigid surfaces, the pressure the rollers exert on the stack of preimpregnated composite material causes in some areas, depending on the geometry of the mandrel, a movement of the resin, reducing its thickness in certain parts of the material, which leads to the material and the corresponding parts formed from it to lose part of their strength characteristics as well as rigidity and dimensional tolerances after curing, which is particularly detrimental in applications of the parts in fields requiring particularly reliable qualities, such as the aeronautical industry for example. Another effect occurring in the roll-formed stacks is the so-called spring back phenomenon, consisting of the tendency to recover the initial geometry of the stack once it has been formed by the forming rollers.
Therefore, in view of the aforementioned and analyzed background document it has been observed that there is a need to provide a system for forming stacks of composite materials that prevents the aforementioned drawbacks, such that said system is capable of forming complex geometries such as those indicted above, which additionally allows applying homogenous pressure on said stacks and additionally gets the geometry obtained after deforming the stack to remain constant over time, without the so-called spring back phenomenon happening.